The invention relates to a drive for a rotatable drum, such as a rotary kiln or a tube mill, in which a gear rim is mounted on, and radially spaced from, the outside of the drum by means of a flexible connection.
It is known to mount a gear rim on a rotatable drum via a flexible connection providing compensation for possible out-of-roundness of the drum and preventing, e.g. thermal, deformation of the drum from causing substantial loads on the gear rim.
From U.S. Pat. No. 2,999,396 there is known a gear rim which is connected to a rotary kiln via leaf springs, the springs being secured at one end to the gear rim and at the other end to the drum.
From FIG. 1 of DE-A-2604425 is known a flexible connection between a gear rim and the outside of a tube mill comprising a tube section disposed coaxially with the tube mill and radially spaced both from the outside of the tube mill and from the gear rim, and being resiliently connected at one end to the tube mill and at the other end to the gear rim. This elastic connection too is intended for compensation for out-of-roundness and thermal deformations of the tube mill casing so as to prevent such deformations from loading the gear rim.
However, none of the known flexible connections are applicable for transferring to the drum axial loads deriving from a bevel toothing of the drive. It is an advantage of bevel toothing as compared with straight toothing that it is possible to make the gear rim considerably narrower for transfer of the same torque. However, an axial load acting on the gear rim of the known drives will cause the gear rim to tilt, with the consequence that the derived line contact between the teeth of the gear rim and those of a complementary driving gear is replaced by point contact with resultant heavily increased local wear on the teeth.